color in renderer for visualization
Hi,
I'm trying to use OpenSCAD to create and visualize 3D-models,
both static ones and animated ones. Using different colors
is crucial here.
Unfortunately, there seems to be no way to keep the colors when
rendering the model.
So, I would like OpenSCAD to be able to render in color. I'm a
programmer, so maybe I could even implement it, but I currently
don't know where to start. I don't know the sourcecode, but
I can think of several ways:
-
Transfer the color-information to CGAL.
CGAL seems to have some color support, and the rendered models already
have two colors: yellow as default, and light green for faces resulting
e.g. from "difference()". It it would be possible to communicate the
color to CGAL and use CGALs color-features, this would be the easiest way. -
Add color-support to CGAL.
If CGALs color-support isn't sufficient, CGAL could be extended, and
then (1) could be done. -
Use a different render-backend than CGAL.
I think it would be too much effort to change the backend just to get
colors. But if (1) and (2) do not work, this one would.
And e.g. a POVRay-backend would be cool, even if (1) or (2) work. ;) -
Use render() as workaround.
I shortly noticed, that rendered objects can be colored:- color("red") cube(100);
-> red cube - render() color("red") cube(100);
-> yellow cube ("no color-support") - color("green") render() color("red") cube(100);
-> green cube (yay, color for rendered objects!)
I haven't used this much, and don't know if there are any pitfalls,
but this seems to make it possible to color rendered objects. And
since this seems to work, I think (1) should work, too. - color("red") cube(100);
Can you tell me, if (1) should work and where I would have to start to
implement it? Or, if I should use one of the other ways (or even a
different one), and where to start then?
best regards
Roland
If you just want a picture you don't need to use CGAL, F5 gives a coloured
render. F6 is for making solid models to export but the file formats don't
have colour anyway.
On 30 June 2015 at 13:18, Roland Koebler rk-list@simple-is-better.org
wrote:
Hi,
I'm trying to use OpenSCAD to create and visualize 3D-models,
both static ones and animated ones. Using different colors
is crucial here.
Unfortunately, there seems to be no way to keep the colors when
rendering the model.
So, I would like OpenSCAD to be able to render in color. I'm a
programmer, so maybe I could even implement it, but I currently
don't know where to start. I don't know the sourcecode, but
I can think of several ways:
-
Transfer the color-information to CGAL.
CGAL seems to have some color support, and the rendered models already
have two colors: yellow as default, and light green for faces resulting
e.g. from "difference()". It it would be possible to communicate the
color to CGAL and use CGALs color-features, this would be the easiest
way. -
Add color-support to CGAL.
If CGALs color-support isn't sufficient, CGAL could be extended, and
then (1) could be done. -
Use a different render-backend than CGAL.
I think it would be too much effort to change the backend just to get
colors. But if (1) and (2) do not work, this one would.
And e.g. a POVRay-backend would be cool, even if (1) or (2) work. ;) -
Use render() as workaround.
I shortly noticed, that rendered objects can be colored:- color("red") cube(100);
-> red cube - render() color("red") cube(100);
-> yellow cube ("no color-support") - color("green") render() color("red") cube(100);
-> green cube (yay, color for rendered objects!)
I haven't used this much, and don't know if there are any pitfalls,
but this seems to make it possible to color rendered objects. And
since this seems to work, I think (1) should work, too. - color("red") cube(100);
Can you tell me, if (1) should work and where I would have to start to
implement it? Or, if I should use one of the other ways (or even a
different one), and where to start then?
best regards
Roland
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Better color handling is a periodic request. My recent analysis revealed it
is not as simple as adding a color property to polygons, the CSG engine must
take account of the color property to properly support it.
I had a look for existing knowledge on adding color to CGAL, but drew a
blank. I also found that color properties require more CSG operations, and
CGAL is quite slow already, so I also wanted to look at swapping out the CSG
back end, also on the long term todo list.
Therefore I am building an experimental Openscad using the Carve library for
CSG, and then later will add support for color and material properties. This
development can be found at https://github.com/bobc/openscad/tree/carve_csg.
This is very much work in progress; it builds with carve lib, but does not
produce any useful output yet. I haven't put carve into qmake system yet, so
libcarve needs to be built separately and copied in.
But as nophead says, do you need to render for your purposes? I'm not sure
how you intend the visualization stage.
--
View this message in context: http://forum.openscad.org/color-in-renderer-for-visualization-tp12952p12955.html
Sent from the OpenSCAD mailing list archive at Nabble.com.
AMF supports color.
There is also a significant chicken and egg here which seems to stifle
progress. While Openscad does not support color, there is little incentive
to implement any of the several formats that do support color. The lack of
those export formats is then used to justify not supporting color in
Openscad...
--
View this message in context: http://forum.openscad.org/color-in-renderer-for-visualization-tp12952p12956.html
Sent from the OpenSCAD mailing list archive at Nabble.com.
what needs to be done to speed up rendering using F6?
now it's all single-threaded, which i believe is the majority of the
"complicated stuff seemingly takes eons to rendah" issue.
i recently installed a mid-range GPU card (Nvidia 760x) and the results
are dramatic decreases (for some software) in render time. but no
bennies using OpenSCAD.
i'm sure others have requested F6 improvements, and iirc i read a
missive somewhere that indicated a new rendering library or other
software needs to be setup in OpenSCAD, and that this is a non-trivial
issue.
can i help with this in any way? please lmk.
On 06/30/2015 02:18 PM, Roland Koebler wrote:
I'm trying to use OpenSCAD to create and visualize 3D-models,
both static ones and animated ones. Using different colors
is crucial here.
Unfortunately, there seems to be no way to keep the colors when
rendering the model.
Yes, currently that's not supported, but it certainly is quite
a big point on the wish-list.
Have a look at http://forum.openscad.org/Semantics-CSG-ops-with-respect-to-color-materials-td12667.html
for some recent discussion.
-
Transfer the color-information to CGAL.
CGAL seems to have some color support, and the rendered models already
have two colors: yellow as default, and light green for faces resulting
e.g. from "difference()". It it would be possible to communicate the
color to CGAL and use CGALs color-features, this would be the easiest way. -
Add color-support to CGAL.
If CGALs color-support isn't sufficient, CGAL could be extended, and
then (1) could be done.
There are other CGAL issues (mainly speed) too, so there is the
idea to switch to a different backend for the CSG operations...
- Use a different render-backend than CGAL.
I think it would be too much effort to change the backend just to get
colors. But if (1) and (2) do not work, this one would.
And e.g. a POVRay-backend would be cool, even if (1) or (2) work. ;)
...but it's probably not going to be easy. There are a number of
options, but nothing yet which really screams "Use me, I'm the
perfect solution".
https://github.com/openscad/openscad/wiki/Project%3A-Survey-of-CSG-algorithms
lists some of the contenders, some are old and barely maintained.
OpenCascade is likely able to do the job, but is probably 50 times
larger than OpenSCAD itself :-).
Another recent discussion about that topic:
http://forum.openscad.org/Odd-ternary-behaviour-2015-05-15-nightly-git-5451fab-td12784.html
-
Use render() as workaround.
I shortly noticed, that rendered objects can be colored:- color("red") cube(100);
-> red cube - render() color("red") cube(100);
-> yellow cube ("no color-support") - color("green") render() color("red") cube(100);
-> green cube (yay, color for rendered objects!)
I haven't used this much, and don't know if there are any pitfalls,
but this seems to make it possible to color rendered objects. And
since this seems to work, I think (1) should work, too. - color("red") cube(100);
That's still only working in preview mode. The render() call forces mesh
generation (evaluate CSG ops) so the result is one single mesh, even in
preview mode. The color around render() works as this is then again painted
via the OpenCSG library. Using F6 to force a full render still removes
the color.
Can you tell me, if (1) should work and where I would have to start to
implement it? Or, if I should use one of the other ways (or even a
different one), and where to start then?
I don't know CGAL well enough to say if (1) is actually possible.
From what I see it's not possible with the data structure we currently
use. Maybe there's some additional stuff somewhere in CGAL.
I guess the best way forward is to join forces with Bob (first forum
link) who is currently investigating this topic. I'm not sure what the
best topic to start with is... there's quite a number of possible options.
There's one task (which is likely a bit boring) which was started
by Bob already. That's isolating CGAL again as the code separation
to build OpenSCAD without CGAL seems to have bitrotted quite a bit.
(http://forum.openscad.org/Building-OpenSCAD-without-CGAL-td12880.html)
This would open up easier ways for trying one or more of the other
existing libraries.
I offer to help with the boring part :-)
ciao,
Torsten.
On 06/30/2015 08:28 PM, bobc wrote:
AMF supports color.
There is also a significant chicken and egg here which seems to stifle
progress. While Openscad does not support color, there is little incentive
to implement any of the several formats that do support color. The lack of
those export formats is then used to justify not supporting color in
Openscad...
OpenSCAD supports AMF and SVG (for 2D) exports.
Also OFF is supported which I think can support color too.
OBJ support is not finished yet, but there's a branch in the repo to add
support and OBJ would support color.
So the egg is already there. Or is it the chicken? :-)
ciao,
Torsten.
I believe we need a new rendering engine.
Primarily, it needs to use floating point, instead of dynamically
allocated, variable length rational numbers.
After that, multi-core support and GPU support (eg, OpenCL) would make it
faster.
I was recently looking at the PLaSM rendering engine.
Written in C++, open source with a GPL3 licence.
It uses floating point, claims to be fast, there are conference papers
about the
algorithms they use, and it might be good robust code
due to the long history of the project (since 1997 or so).
One interesting feature of the engine is "progressive preview", where it
shows you progressively more detailed renders of the model during preview.
They haven't released an open source progressive previewer, though, and it
might not be easy to take advantage of the feature. Still, I like the idea
of
progressive preview, since some models will always take an hour to preview
no matter how fast the engine. People will just start creating more complex
models.
No general minkowski sum. Lots of other interesting primitives that we
don't have,
including the ability to use 1D and 2D shape objects. Their cylinder
primitive
is implemented by computing the cartesian product of a 2D circle and a 1D
line segment.
Doug.
On 30 June 2015 at 14:37, Yvette S. Hirth, CCP, CDP yvette@dbtgroup.com
wrote:
what needs to be done to speed up rendering using F6?
now it's all single-threaded, which i believe is the majority of the
"complicated stuff seemingly takes eons to rendah" issue.
i recently installed a mid-range GPU card (Nvidia 760x) and the results
are dramatic decreases (for some software) in render time. but no bennies
using OpenSCAD.
i'm sure others have requested F6 improvements, and iirc i read a missive
somewhere that indicated a new rendering library or other software needs to
be setup in OpenSCAD, and that this is a non-trivial issue.
can i help with this in any way? please lmk.
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Here's a link to the project page for speeding up F6.
Actually, it's for the initial research component,
as we haven't chosen a new rendering engine yet.
https://github.com/openscad/openscad/wiki/Project%3A-Survey-of-CSG-algorithms
On 30 June 2015 at 14:37, Yvette S. Hirth, CCP, CDP yvette@dbtgroup.com
wrote:
what needs to be done to speed up rendering using F6?
now it's all single-threaded, which i believe is the majority of the
"complicated stuff seemingly takes eons to rendah" issue.
i recently installed a mid-range GPU card (Nvidia 760x) and the results
are dramatic decreases (for some software) in render time. but no bennies
using OpenSCAD.
i'm sure others have requested F6 improvements, and iirc i read a missive
somewhere that indicated a new rendering library or other software needs to
be setup in OpenSCAD, and that this is a non-trivial issue.
can i help with this in any way? please lmk.
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
BobC is investigating changes to OpenSCAD that will make it easier to
replace CGAL with an alternate geometry engine.
That's another step towards faster F6.
http://forum.openscad.org/Building-OpenSCAD-without-CGAL-td12880.html
On 30 June 2015 at 14:37, Yvette S. Hirth, CCP, CDP yvette@dbtgroup.com
wrote:
what needs to be done to speed up rendering using F6?
now it's all single-threaded, which i believe is the majority of the
"complicated stuff seemingly takes eons to rendah" issue.
i recently installed a mid-range GPU card (Nvidia 760x) and the results
are dramatic decreases (for some software) in render time. but no bennies
using OpenSCAD.
i'm sure others have requested F6 improvements, and iirc i read a missive
somewhere that indicated a new rendering library or other software needs to
be setup in OpenSCAD, and that this is a non-trivial issue.
can i help with this in any way? please lmk.
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org